Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
  • B27K3/34—Organic impregnating agents
  • B27K3/50—Mixtures of different organic impregnating agents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/06—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to wood
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
  • B27K3/34—Organic impregnating agents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K5/00—Treating of wood not provided for in groups B27K1/00, B27K3/00
  • B27K5/02—Staining or dyeing wood; Bleaching wood
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D15/00—Woodstains
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/4935—Impregnated naturally solid product [e.g., leather, stone, etc.]
  • Y10T428/662—Wood timber product [e.g., piling, post, veneer, etc.]

Definitions

• the present invention relates to a method of effectively resisting undesired discoloration of wood and wood products and, more specifically, it relates to such a method which employs a polydentate amino carboxylic acid and/or a dialkyl diphosphonic acid in wood preservative solutions including, but not limited to, those treated with wood preservative solutions, stains or coatings to resist unwanted discoloration of wood and wood products.
• Chemicals used in wood preservation may include fungicides, insecticides, decay-resistant materials, stain-resisting materials, weather proofing materials, and fire retardants and combinations thereof. See, for example, United States Patent numbers 4,879,083; 4,950,685; 5,468,284; 5,763,338; 5,883,741;5,855,817;
• United States Patents 7,896,960 and 7,655,281 disclose a method of protecting wood through enhanced penetration of wood preservatives by providing a solution which includes at least one amine oxide, at least one organic wood preservative and a buffering agent.
• the buffering agent may be selected from the group consisting of borates, boric acids, phosphates, calcium hydroxide, and combinations thereof.
• United States Patent Application 13/079,905 discloses a method that permits enhanced penetration of wood preservatives through the use of solutions having a buffered pH above the pH of the wood achieved through the use of a combination of amine oxide and a non-borate buffering agent.
• the present invention resists discoloration of wood by the inclusion of stain-blocking material(s) in a primer, coating or top-coat that is applied to the wood surface.
• stain-blocking material(s) in a primer, coating or top-coat that is applied to the wood surface.
• the remediation of discolored wood to resist additional discoloration is typically realized through physical or chemical methods or a combination of both methods.
• the stain blocking solution is introduced in combination with a wood preservative which penetrates into the interior of the wood so as to resist movement and deposition of organic based chromophoric molecules onto the wood surface, thereby contributing to undesired discoloration.
• the stain blocking additive When employed with a wood preservative, the stain blocking additive is preferably mixed with the wood preservative prior to application, but in a less preferred approach, may be applied to the wood for penetration thereinto before or after the wood preservative is introduced.
• the stain blocking materials may also be used apart from use with wood preservatives to resist the undesired discoloration of the wood.
• the polydentate amino carboxylic acid or the dialkyl phosphonic acid may be employed separately in the discoloration resistant additive solution of the present invention, it is preferred that a combination of the two be employed. All the percentages mentioned refer to a weight to weight ratio, i.e. mass of additive to mass of total wood preservative solution.
• the polydentate amino carboxylic acid may be employed in a weight percent based on the entire wood preservative solution of about 0.1 to 15% and preferably about 0.1 to 10%.
• the dialkyl diphosphonic acid may be employed in the range of 0.1 to 10% weight percent and preferably about 1 to 5.0% of the weight of the total wood preservative solution.
• the discoloration resisting additive is introduced into the wood preservative before it is applied to the wood or it is provided shortly before or shortly after the wood preservative is applied.
• the preferred approach would be to introduce the discoloration resisting solution into the wood preservative prior to application to the wood.
• the polydentate amino carboxylic acid may be mixed with the dailkyl diphosphonic acid with the former being present in an amount of about 0.1 to 5 percent and the latter being applied in the amount of about 1 to 3 percent all based upon the total weight of the discoloration resistant additive.
• polydentate amino carboxylic acid in instances where polydentate amino carboxylic acid is employed without the dailkyl diphosphonic acid, it may be employed in about 0.1 to 15 weight percent based upon the total wood preservative solution and preferably about 0.1 to 10 percent. Where the dailkyl diphosphonic acid is employed alone, it may be employed in the range of about 0.1 to 10 weight percent based upon the total wood preservative solution weight and preferably about 1 to 5 percent.
• the method of the present invention permits the resisting of discoloration in wood and wood products through the inclusion of polydentate amino carboxylic acid and/or a dialkyl diphosphonic acid in the wood preservation solution, stain or coating to resist the migration of unwanted chromophoric molecules to wood surface and subsequent discoloration. While a coating would not provide the preferred depth of penetration such as presented by a wood preservation solution or stain, it,
• the wood preservative solution containing this polydentate amino carboxylic acid and/or a dialkyl diphosphonic acid would be used to impregnate the key chemicals described herein which are introduced into the wood.
• this invention relates to a method of protecting wood against discoloration by treatment with a wood preservative, stain, coating, or impregnation of the wood comprising at least one acid selected from the group consisting of polydentate monoamino carboxylic acid of formula I and polydentate polyamino carboxylic acid of formula II and a dialkyl diphosphonic acid of formula III.
• X is independent and can be linear, branched, cyclic, aromatic or any combination thereof saturated or unsaturated CI to C20 group and any C1-C20 carbon atom can be replaced with a heteroatom selected from the group consisting of 0, S, Si and N.
• Y is a carboxylic acid group or a carboxylate anion paired with any metallic or nonmetallic cation.
• Zi and Z 2 are each a methyl group, or Zi and Z 2 together may form a linking moiety which may additionally be substituted by an ester, ether, hydroxyl, oxo, cyanohydrin, amide, amino, carboxy or urethane group.
• N is a nitrogen atom
• P is a phosphorous atom
• the invention also contemplates the treating solution per se and the wood which has been so treated.
• a wood preservative solution is created with a discoloration resisting additive with at least one acid selected from the group consisting of polydentate amino carboxylic acid and a dialkyl diphosphonic acid along with the wood preservative(s), primer or top-coat which is to be applied to the wood.
• This solution may have a pH of about 5 to 12.4 and preferably about 6 to 10 and most preferably about 6.5 to 8.5.
• the wood preservative solution may be applied to the surface of the wood by any desired means. It is preferred that the application be at a solution temperature of 30°C to 75°C. The wood may also be heated before and/or after application of the solution to enhance penetration of the wood preservative solution. If desired, pressure or vacuum may be employed to facilitate penetration. [0019] It is an object of the present invention to provide solutions for resisting undesired discoloration of wood and related methods of application and wood products provided with such resistance.
• the depth of penetration into the wood of each may be to a different level, but in general, will allow for the deposition of the polydentate amino carboxylic acid and a dialkyl diphosphonic acid below the outermost surface as to resist migration of the chromophoric molecules and subsequent discoloration to the exterior surface.
• discoloration resisting material may be applied before or after the wood preservative materials.
• wood means wood, wood-based materials, wood fiber materials, forest products, timber, lumber, green lumber, engineered wood, millwork, joinery, wood laminates, laminated veneer lumber, plywood, laminated strand lumber, wood fiber composites, medium density fiberboard, particle board, hard board, oriented strand board, wood fiber resin composites, wood strand resin composites, wood particle resin composites and other wood and wood fiber-based materials and fabricated and semi-fabricated products made therefrom.
• wood preservative means organic compounds, halo-organic compounds, metalo-organic compounds, organo-salts, metal salts, borates, organophosphates and non-organoboron compounds having fungicidal, insecticidal, water-resistant, termite-resisting, decay-resisting, stain-resisting or other wood-protective properties.
• wood preservative solution means an organic solvent or aqueous based solution, emulsion or dispersion containing a wood preservative or combination of wood preservatives and optionally, in addition, chemicals such as suitable solvents, amine oxides, water repellents, waxes, polymers, silicones, coloring agents or dyes may be included.
• stain refers to any organic solvent or aqueous based solution that contains colorants intended to alter the surface color of wood.
• coating refers to any organic or aqueous based resin system that is intended to serve as a thin film protective layer to the wood surface and includes primer paints, top-coat paints, sealants, shellacs, varnish, enamel paints and any paint product intended for final use as a dry film coating after application.
• polydentate amino carboxylic acid refers to those compounds which are formed as reaction products of amines, aldehydes and cyanides and are represented by the general formula(s) I and II.
• dialkyl diphosphonic acid refers to those compounds which are formed as reaction products from the condensations of aldehydes and polyalkyl phosphites or from transesterfication and are represented by the general formula III.
• X is independent and can be linear, branched, cyclic, aromatic or any combination thereof saturated or unsaturated C 1 to C20 group and any CI -C20 carbon atom can be replaced with a heteroatom selected from the group consisting of 0, S, Si and N.
• Y is a carboxylic acid group or a carboxylate anion paired with any metallic or nonmetallic cation.
• Zi and Z 2 are each a methyl group, or Z ⁇ and Z 2 together may form a linking moiety which may additionally be substituted by an ester, ether, hydroxyl, oxo, cyanohydrin, amide, amino, carboxy or urethane group.
• N is a nitrogen atom
• P is a phosphorous atom
• Preferred polydentate amino carboxylic acids are nitrilotriacetic acid, ethylene diaminetetraacetic acid and diethylene triaminepentaacetic acid.
• a wood preservative solution, stain or top-coat contains a combination of the polydentate amino carboxylic acid and a dialkyl diphosphonic acid having a pH of about 4 to 12.5 and preferably about 5 to 10 and most preferably about 6.5 to 8.
• the compounds listed in this invention may be provided in concentrate form in a solution, slurry, emulsion or dispersion utilizing a suitable solvent, such as water, with the final solution to a be applied being created by adding additional solvent and mixing the same in order to minimize shipping and storing of the volume required to make up the difference between the concentrate solvent volume and the final solvent volume.
• a suitable solvent such as water
• the wood preservative solution, stain or coating preferably contains about 0.10 to 15 weight percent based on weight of the total solution of one or more of the polydentate amino carboxylic acids and most preferably about 0.1 to 10 weight percent based on weight of the total solution , in addition to about 0.10 to 10 weight percent based on weight of the total solution of one or more of the dialkyl diphosphonic acids and most preferably about 1 to 5 weight percent, all based on mass of total solutions.
• ammonium pentaborate reduces the severity of yellowing when paired with additive chemicals of the invention, the reduction in severity is amplified. It is preferred that the ammonium pentaborate be employed in about 0.1 to 2 % and preferably about 5 to 15% of the total solution and weight basis whether the solution contains a wood preservative and/or the discoloration additive.
• the wood preservative may be present in the wood preservative solution in about 3 ppm to 50 weight percent based on weight of total solution and preferably about 20 ppm to 5,000 ppm.
• the wood preservative solution, stain or top-coat is in water or organic solvents such as ethanol or ethylene glycol, for example.
• the materials may be provided in the form of a concentrate which will be diluted prior to application to achieve the forgoing relationships.
• the wood preservative solution, stain or coating may be applied to the wood by any desired means such as spraying, rolling on or dipping, for example.
• pressure or vacuum can be used to deliver the wood preservative solution containing the polydentate amino carboxylic acid and/or a dialkyl diphosphonic acid.
• the wood so treated may be stored for a period of time before additional processing. For example, the wood may be covered for about 12 to 24 hours after application to the wood which is at about 12°C to 100 °C.
• Application may be achieved at any temperature between ambient and boiling temperature, but in the preferred approach to this invention, application of the wood preservative solution containing the polydentate amino carboxylic acid and/or dialkyl diphosphonic acid will be achieved at a temperature of about 30°C to 75°C and most preferably at a temperature of about 40°C to 65°C; application of stains or coatings containing the about 30°C to 75°C will be preferably achieved at about 25°C to 40°C. It is preferred to heat the wood to about 8°C to 230°C prior to application and most preferably about 12°C to 100°C.
• wood preservative solution stain or coating
• ranges set forth herein refer to each category with a single compound or category of compounds.
• the method of the present invention may be practiced in an in-line manner to process the wood efficiently or in a pressure-vacuum impregnation method with the method effecting unwanted discoloration of wood.
• the wood may be engineered wood or laminated wood having a glued layer or substantial amount of glue or resin therein with the method effecting unwanted discoloration of wood.
• the method may be performed on wood with any amount of moisture content including green (wet) wood and on wood which has moisture at a level which does not exceed the fiber saturation point of the wood and on dry wood.
• the propensity for discoloration of wood may be evaluated utilizing accelerated heat and humidity in a chamber designed to operate at 60°C ( ⁇ 3°C) oven at >95% relative humidity over a standard test duration of 168 h.
• white-primer 3-5 wet mils thick was applied on the sample boards to serve as a standard background for color comparison prior to the torture testing. Results from this accelerated torture are quantified utilizing an assigned color ranking scale of 0-15 where any affected surface area of the wood is noted. Colors for comparison were taken from standard commercial colorants that range from light yellow to dark brown. To ensure that the data captured both heartwood and sapwood, any minor discoloration was recorded as an overall sample discoloration. A minimum of seven separate samples was scored and averaged to one composite score for reporting herein. Commercial Color Codes and Correlation to Inventors Discoloration
• the first column contains references to a commercially available color code with the Ranking being established as correlating with the various color standards.
• the indication of "No Discoloration” was given the ranking of 0, the next higher level of discoloration designated BHG601 was given a ranking of 1.
• the yellow background with Table 1 discoloration became more intense.
• the BHG (Better Homes & Gardens) standard related to hues of yellow which is the predominate color experience with discoloration of wood was employed
• sugar pine is a type of wood known to create undesired discoloration problems, it was selected for use in the present examples.
• Other woods which are highly susceptible to undesired discoloration are Lodgepole Pine and Douglas fir.
• the samples contained a fair portion of heartwood. The wood qualified as
• Weatherboard is a wood of decent quality and is employed for uses such as exterior trim applications on houses, for example.
• a wood preservative solution containing 1062.0 grams of a borate buffered, aqueous amine-oxide containing wood preservative solution was heated to 60°C (+2°C) and stirred until homogeneous. 21.21 grams of nitrilotriacetic acid was added and the solution was allowed to stir at 60°C (+2°C) until homogeneous.
• Sugar Pine lumber of the dimensions approximately 20 mm deep, 140 mm wide and 128 mm long was immersed for 1 second in the hot wood preservative solution. The samples were then placed in a suitable plastic covering for 12-24 h at 40°C ( ⁇ 2°C) before unwrapping and drying the samples for 1 -2 h at room temperature and humidity.
• Standard commodity white primer was applied to approximately one-half of the surface area of the sample to 3-5 wet mils thickness by brush application over two coats with approximately 45 min dry time between applications of the second coat.
• the samples were dried for a minimum of 12 h at ambient temperature and humidity.
• the samples were then placed in a 60°C (+2°F) oven at >95% relative humidity for 168 h before removing and drying at room temperature for 1-2 h for comparison.
• Wood preservative contain ingredients which assist chemicals in getting deep into the wood. These same chemicals help things to get out.
• a wood preservative may use a buffer to temporarily block the cellulose and lignin functionalities that can deter organic molecules from migrating into the wood. When coupled with the amine oxide carrier molecules employed in the examples this creates a good environment for enhanced penetration into the wood.
• chromophoric molecules are now more easily migrated to the surface because the wood is primed with the buffers and amine oxides. Eventually, the wood acids overcome the buffers and the propensity to act as normal is restored.
• a wood preservative containing 886.0 grams of a borate buffered, aqueous amine-oxide containing wood preservative solution was heated to 60°C (+2°C). The solutions were heated to 60°C (+2°C) and stirred until homogeneous. 8.97 grams of 1- hydroxyethylidene-1, 1-diphosphonic acid was added and the solution was allowed to stir at 60°C ( ⁇ 2°C) until homogeneous.
• Sugar Pine lumber, of the dimensions approximately 20 mm deep, 140 mm wide and 128 mm long was immersed for 1 second in the hot wood preservative system.
• the samples were then placed in a suitable plastic covering for 12-24 h at 40°C ( ⁇ 2°C) before unwrapping and drying the samples for 1-2 h at room temperature and humidity.
• Standard commodity white primer was applied to approximately one-half of the surface area of the sample to 3-5 wet mils thickness by brush application over two coats with approximately 45 min dry time between applications of the second coat.
• the samples were dried for a minimum of 12 h at ambient temperature and humidity.
• the samples were then placed in a 60°C (+2°F) oven at >95% relative humidity for 168 h before removing and drying at room temperature for 1-2 h for comparison.
• the samples were then placed in a suitable plastic covering for 12 _, 24 h at 40°C ( ⁇ 2°C) before unwrapping and drying the samples for 1-2 h at room temperature and humidity.
• Standard commodity white primer was applied to approximately one-half of the surface area of the 20 mm deep, 140 mm wide and 128 mm long sample to 3-5 wet mils thickness by brush application over two coats with approximately 45 min dry time between applications of the second coat.
• the samples were dried for a minimum of 12 h at ambient temperature and humidity.
• the samples were then placed in a 60°C (+2°F) oven at >95% relative humidity for 168 h before removing and drying at room temperature for 1-2 h for comparison.
• the samples were then placed in a suitable plastic covering for 12-24 h at 40°C ( ⁇ 2°C) before unwrapping and drying the samples for 1 -2 h at room temperature and humidity.
• Standard commodity white primer was applied to approximately one-half of the surface area of the sample to 3-5 wet mils thickness by brush application over two coats with approximately 45 min dry time between applications of the second coat.
• the samples were dried for a minimum of 12 h at ambient temperature and humidity.
• the samples were then placed in a 60°C (+2°F) oven at >95% relative humidity for 168 h before removing and drying at room temperature for 1-2 h for comparison.
• Sugar Pine lumber of the dimensions approximately 20 mm deep, 140 mm wide and 128 mm long was immersed for 1 second in the hot wood preservative system.
• the samples were then placed in a suitable plastic covering for 12-24 h at 40°C (+2°C) before unwrapping and drying the samples for 1-2 h at room temperature and humidity.
• Standard commodity white primer was applied to approximately one -half of the surface area of the sample to 3-5 wet mils thickness by brush application over two coats with approximately 45 min dry time between applications of the second coat.
• the samples were dried for a minimum of 12 h at ambient temperature and humidity.
• the samples were then placed in a 60°C (+2°F) oven at >95% relative humidity for 168 h before removing and drying at room temperature for 1-2 h for comparison.
• Standard commodity white primer was applied to approximately one-half of the surface area of the sample to 3-5 wet mils thickness by brush application over two coats with approximately 45 min dry time between applications of the second coat.
• the samples were dried for a minimum of 12 h at ambient temperature and humidity.
• the samples were then placed in a 60°C (+2°F) oven at >95% relative humidity for 168 h before removing and drying at room temperature for 1-2 h for comparison.
• 7 samples extracted from uniform parent boards treated with both the wood preservative and the discoloration resistant solution of this invention were evaluated and an average discoloration score of 2.5 was evidenced.
• the untreated samples were evaluated and an average discoloration of 3.2 was shown.
• Seven samples from the same uniform boards treated with the same wood preservative solution without the compounds described in this invention reported an average discoloration score of 3.0. The variations in these results is attributable to the different wood that was utilized and the variability and
• Standard commodity white primer was applied to approximately one-half of the surface area of the sample to 3-5 wet mils thickness by brush application over two coats with approximately 45 min dry time between applications of the second coat.
• the samples were dried for a minimum of 12 h at ambient temperature and humidity.
• the samples were then placed in a 60°C (+2°F) oven at >95% relative humidity for 168 h before removing and drying at room temperature for 1-2 h for comparison.
• 7 samples extracted from uniform parent boards treated with both the wood preservative and the discoloration resistant solution of this invention were evaluated and an average discoloration score of 2.5 was evidenced.
• Seven samples from the same uniform boards treated with the same wood preservative solution without the compounds described in this invention reported an average discoloration score of 3.0.
• This example shows how the undesired discoloration solution additive of the present invention can be incorporated into a wood preservative system which in turn can be placed in a primer system used on the same treated wood.
• nitrilotriacetic acid was added and stirred until homogeneous. No impractical increase in working viscosity was noted.
• the additive can be added during the pigment grinding process for better incorporation.
• the primer containing the additive was applied to approximately one-half of the surface area of the sample to 3-5 wet mils thickness by brush application over two coats with approximately 45 min dry time between applications of the second coat.
• the samples were dried for a minimum of 12 h at ambient temperature and humidity.
• the samples were then placed in a 60°C (+2°F) oven at >95% relative humidity for 168 h before removing and drying at room temperature for 1-2 h for comparison.
• nitrilotriacetic acid was added and stirred until homogeneous. No impractical increase in working viscosity was noted.
• the additive can be added during the pigment grinding process for better incorporation.
• the primer containing the additive was applied to approximately one-half of the surface area of the sample to 3-5 wet mils thickness by brush application over two coats with approximately 45 min dry time between applications of the second coat.
• the samples were dried for a minimum of 12 h at ambient temperature and humidity.
• the samples were then placed in a 60°C (+2°F) oven at >95% relative humidity for 168 h before removing and drying at room temperature for 1-2 h for comparison.
• the method of the present invention provides an efficient, safe, economically feasible method of resisting unwanted discoloration in wood and wood products as a result of the unique combination of polydentate aminocarboxylic acid and dialkyl diphosphonic acid in wood preservative solutions, stains and coatings intended for application on wood and wood products.

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Chemical & Material Sciences (AREA)
• Forests & Forestry (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Chemical And Physical Treatments For Wood And The Like (AREA)

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• 2012
  • 2012-04-25 US US13/455,843 patent/US20130288067A1/en not_active Abandoned
• 2013
  • 2013-04-09 AU AU2013252821A patent/AU2013252821A1/en not_active Abandoned
  • 2013-04-09 EP EP13781440.6A patent/EP2841212A1/fr not_active Withdrawn
  • 2013-04-09 BR BR112014026842A patent/BR112014026842A2/pt not_active Application Discontinuation
  • 2013-04-09 CA CA 2870827 patent/CA2870827A1/fr not_active Abandoned
  • 2013-04-09 WO PCT/US2013/035692 patent/WO2013162865A1/fr not_active Ceased
• 2014
  • 2014-10-24 CL CL2014002874A patent/CL2014002874A1/es unknown
  • 2014-11-11 US US14/538,257 patent/US20150125712A1/en not_active Abandoned

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